Quasi progressive lenses for eyewear

ABSTRACT

Various embodiments disclose a quasi progressive lens including a first optical zone capable of providing distance vision, a second optical zone capable of providing near vision and a transition zone connecting the first and second optical zones. Physical dimensions (e.g., length and width) of the transition zone are adjusted to increase the size of the second optical zone in comparison to progressive lenses and to reduce residual cylinder power and aberrations along the convergence path in comparison to bifocal lenses.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.14/274,637, filed May 9, 2014, which claims benefit under 35 U.S.C.§119(e) of U.S. Provisional Application No. 61/971,469, filed on Mar.27, 2014, titled “Quasi Progressive.” This application also claimsbenefit under 35 U.S.C. §119(e) of U.S. Provisional Application No.61/938,029, filed on Feb. 10, 2014, titled “BIFOCAL LENS.” Thedisclosure of each of the above identified applications is incorporatedby reference herein in their entirety.

BACKGROUND OF THE INVENTION Field of the Invention

This description relates generally to ophthalmic lenses used in eyewearthat provide near vision as well as distance vision correction.

Description of the Related Art

Refractive errors are the most frequent eye problems encountered bypatients of all ages. Refractive errors include (i) myopia ornear-sightedness, a condition in which objects at a far distance (e.g.,at a distance greater than 20 feet) appear blurred; (ii) hyperopia orfarsightedness in which in which objects at a near distance (e.g., at adistance less than 2 feet) appear blurred; (iii) astigmatism in whichobjects at near distance, far distance as well as intermediate distanceappear blurred; and (iv) presbyopia that includes loss of the ability ofthe eye to focus on near objects. These and other refractive errors canbe corrected, for example, by ophthalmic lenses such as those used ineyeglasses.

Patients suffering from hyperopia that also suffer from presbyopia ormay require a first pair of ophthalmic lenses that provide distancevision and a second pair of ophthalmic lenses that provide near vision.Bifocal lenses can correct both near and far vision with the same lensand eliminate the need for separate pairs of ophthalmic lenses forviewing objects at near and far distances. Presbyopic patients can alsobenefit from progressive lenses that can correct near, intermediate andfar vision.

SUMMARY OF THE INVENTION

Bifocal lenses can correct both far and near vision with the same lens.Bifocal lenses include a first optical zone that provides correction forfar or distance vision and a second optical zone that provide correctionfor near vision. The second zone is usually disposed more nasally in thelower portion of the lens. Bifocal lenses available in the market todayhave several disadvantages. For example, as the patient's gaze movesfrom far vision to near vision, a patient can experience loss of imageand abrupt jump in the image. Moreover, the transition between the firstand second optical zones of available bifocal lenses can have unwantedaberrations that can reduce visual quality and cause vision discomfort.In addition, in many available bifocal lenses, the first and secondoptical zones may be separated by a visible dividing line, which may beaesthetically unappealing. Furthermore, while bifocal lenses may be ableto correct distant and near vision, they may be unable to provide goodquality vision at intermediate distances. Progressive lenses canovercome some of the disadvantages of bifocal lenses. For example, manyavailable progressive lenses include a corridor between the firstoptical zone that provides far or distance vision and the second opticalzone that provides near vision. The optical power in the corridor cangradually increase as the gaze moves from far vision to near vision suchthat objects at intermediate distances between far and near distance canbe viewed comfortably through the corridor. However, in someimplementations of progressive lenses, the second optical zone providingnear vision may occupy a smaller portion of the total area of the lens,which can result in degrading the visual experience associated withviewing objects located at near distances. In some implementations ofprogressive lenses, the corridor can be long and/or wide. In variousembodiments, elongating the corridor may lead to reduce residualcylinder power or aberrations in the first optical zone, the secondoptical zone and/or in the peripheral zone, while widening the corridorcan lead to a strengthening of residual cylinder power or aberrations inthese areas. Additionally, in implementations of progressive lenseshaving long corridors, the patient may have to lower the gaze to such anextent that may be uncomfortable for use when transitioning from farvision state to near vision state and vice-versa.

Nevertheless, various lens embodiments described herein provide anophthalmic solution that offers the user improved vision at near and fardistances while increasing the portion of the total area occupied by thefirst and second optical zones providing far and near vision. Suchlenses can also reduce visual distortions when the patient's gazetransitions from far vision to near vision in comparison to bifocalssuch as blended bifocals. The embodiments disclosed herein include aquasi progressive ophthalmic solution (such as, for example, lensblanks, eyeglass lenses, and glasses for eyewear) that include a shortand a narrow transition zone between the first and second optical zonesthat provide near and distance vision. As a result of the reduction inthe width and/or length of the transition zone, the percentage of thetotal area occupied by the first and the second optical zones providingfar and particularly near vision can increase as compared to progressivelenses. Another consequence of reducing the width and/or length of thetransition zone is a decrease in the residual cylinder power in thefirst and the second optical zones and/or the peripheral zones such thatthe visual quality at far and near distances is increased over thevisual quality provided by available progressive lenses. Variousembodiments described herein provide a lens having a residual cylinderpower, power gradient and/or vertical prism gradient along theconvergence path that is significantly lower than available bifocallenses. Yet another advantage of reducing the length of the transitionzone is that a patient can transition from far vision to near vision andvice versa with less movement of the gaze as compared to progressivelenses. In various implementations of the quasi progressive ophthalmicsolution, the transition zone can have large optical power gradient suchthat objects at intermediate distances cannot be viewed or gazedcomfortably through the transition zone. In various implementations ofthe quasi progressive ophthalmic solution, the transition zone can beoptically non-functional such that objects at intermediate distancesappear blurred, distorted and/or unclear. In some instances, objects atintermediate distances cannot be resolved when viewed through theoptically non-functional transition zone.

One innovative aspect of the subject matter described in this disclosurecan be implemented in an ophthalmic lens comprising a far optical zonecapable of providing far vision, a near optical zone capable ofproviding near vision and a corridor connecting the far optical zone andthe near optical zone. The near optical zone has a width between about12 mm and about 40 mm.

Another innovative aspect of the subject matter described in thisdisclosure can be implemented in an ophthalmic lens comprising a faroptical zone capable of providing far vision, a near optical zonecapable of providing near vision and a corridor connecting the faroptical zone and the near optical zone. The corridor can have a lengthbetween about 3 mm and about 8 mm.

Yet another innovative aspect of the subject matter described in thisdisclosure can be implemented in an ophthalmic lens comprising a faroptical zone capable of providing far vision, a near optical zonecapable of providing near vision and a transition zone connecting thefar optical zone and the near optical zone. The transition zone has apower gradient extending from the far optical zone to the near opticalzone with lower power closer to the far optical zone and higher powercloser to the near optical zone. The power gradient can have a valuebetween about 0.05 D/mm and about 1.25 D/mm.

An innovative aspect of the subject matter described in this disclosurecan be implemented in an ophthalmic lens comprising a far optical zonecapable of providing far vision, a near optical zone capable ofproviding near vision, said near optical zone for providing addition anda transition zone connecting the far optical zone and the near opticalzone. The near optical zone has (i) a near reference point (NRP) or (ii)a centroid of the area in the near optical zone in which the addition isnot less than the maximum addition minus 0.25. The near optical zone hasa horizontal width as measured through (i) the near reference point or(ii) said centroid, said horizontal width extending across the nearoptical zone over a distance where the addition is not less than themaximum addition value minus 0.25 D. The horizontal width is betweenabout 12 mm and about 40 mm.

One innovative aspect of the subject matter described in this disclosurecan be implemented in an ophthalmic lens comprising a far optical zonecapable of providing far vision, a near optical zone capable ofproviding near vision, said near optical zone for providing an additionbetween 1.75 D and 4 D and a transition zone connecting the far opticalzone and the near optical zone. The far optical zone has a fitting point(FP) and a horizontal width as measured through the fitting point acrossthe far optical zone over a distance where residual cylinder is not morethan 0.5 D. The horizontal width can be between about 30 mm and about 70mm.

Another innovative aspect of the subject matter described in thisdisclosure can be implemented in an ophthalmic lens comprising a faroptical zone capable of providing far vision, a near optical zonecapable of providing near vision and a transition zone connecting thefar optical zone and the near optical zone. The far optical zone has ahorizontal width as measured across the widest portion of the faroptical zone that is between about 30 mm and about 70 mm.

BRIEF DESCRIPTION OF THE DRAWINGS

Understanding of the present invention will be facilitated byconsideration of the following detailed description of the preferredembodiments of the present invention taken in conjunction with theaccompanying drawings, in which like numerals refer to like parts.

FIG. 1 shows a schematic representation of an embodiment of a flat-topbifocal lens.

FIG. 2 shows a schematic representation of an embodiment of a blendedbifocal lens.

FIG. 3(a) is a schematic illustration of an embodiment of a progressivelens further illustrating the residual cylinder power or aberrations inthe peripheral zones of the lens. FIG. 3(b) illustrates a schematiccontour plot of the addition power in the different portions of theembodiment of progressive lens shown in FIG. 3(a).

FIGS. 4(a) and 4(b) schematically illustrate different embodiments ofquasi progressive lenses.

FIGS. 5(a), 5(b) and 5(c) schematically illustrate cross-sectional viewsof an embodiment of a flat-top bifocal lens, an embodiment of a blendedbifocal lens, and an embodiment of a quasi progressive lens,respectively.

FIG. 6(a) schematically illustrates a technique of measuring the lengthof the transition zone included in a quasi progressive lens. FIG. 6(b)schematically illustrates a technique of measuring the width of thetransition zone included in a quasi progressive lens.

FIGS. 7(a) and 7(b) illustrate maps of the residual cylinder power oraberrations in various optical zones for an embodiment of a blendedbifocal lens and a quasi progressive lens, respectively.

FIGS. 8(a) and 8(b) illustrate the variation of the optical additionpower and the residual cylinder power as a function of view angle invarious optical zones for an embodiment of a blended bifocal lens and anembodiment of a quasi progressive lens respectively.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

It is to be understood that the figures and descriptions of the presentinvention have been simplified to illustrate elements that are relevantfor a clear understanding of the present invention, while eliminating,for the purpose of clarity, many other elements found in typical lenses,lens design and/or manufacturing methods, and eyewear. Those of ordinaryskill in the arts can recognize that other elements and/or steps aredesirable and may be used in implementing the embodiments describedherein.

As used herein, the term “fitting point” may indicate a point on a lensas mounted in a spectacle frame, aligned with the patient's center ofthe pupil in its distance viewing position when the patient is lookingstraight ahead.

The term “clean” used in reference with an optical zone or areaincluding a powered surface indicates that optical zone or area hasresidual cylinder power or aberrations below a threshold (e.g., lessthan 1.0 Diopter, less than 0.75 Diopter, less than 0.5 Diopter, lessthan about 0.25 Diopter, less than about 0.12 Diopter, less than about0.06 Diopter, less than about 0.03 Diopter, etc.).

The term “visual distortion” as used herein is a result of unwanted orresidual cylinder and as such is quantified using residual cylinderpower.

The term “residual cylinder power” or “residual cylinder” is used hereinconsistently as understood by those skilled in the art to indicate thecylinder power obtained by subtracting any prescribed cylinder powerfrom the total cylinder power. Such calculations are known by oneskilled in the art.

The term “far vision” or “distance vision” as used herein indicates therefraction correction the eye of a patient requires from a visioncorrecting lens when viewing objects at a distance greater than about 20feet while the patient uses no accommodation. The term “near vision” asused herein indicates the refraction correction the eye of a patientrequires from a vision correction lens when viewing objects at adistance of about 16 inches, taking into account the patient'saccommodation ability. The term “far optical zone” or “far zone” as usedherein refers to the optical zone or area that is configured to providedistance vision. The term “near optical zone” or “near zone” as usedherein refers to the optical zone or area that is configured to providenear vision.

The term “near reference point” is used herein consistently as set forthin ANSI 3.21.3 standard and indicates the point on a lens as specifiedby the manufacturer at which the addition of power is measured.

As used herein, the terms “slope” and “gradient” can be usedinterchangeably. As used herein optical power is measured in Diopter andcan be expressed with units of “Diopter” or “D”. As used herein theterms “add power” “addition” and “addition power” can be usedinterchangeably. As used herein the terms “corridor” and “transitionzone” can be used interchangeably. As used herein the terms “segment”and “zone” can be used interchangeably.

Various bifocal lenses available in the market today include (a)flat-top bifocal lens and (b) blended bifocal lens. FIG. 1 shows aschematic representation of an embodiment of a flat-top bifocal lens.The illustrated embodiment of a flat-top bifocal lens includes a firstoptical zone 101 that is capable of providing distance or far vision anda second optical zone 103 that is capable of providing near vision. Thefirst optical zone 101 has optical properties such that it is capable ofproviding distance vision (e.g., at far distances greater than 20 feet).The second optical zone 103 has optical properties such that it iscapable of providing near vision (e.g., at near distances of about 16inches). A visible dividing line 105 separates the first optical zone101 and the second optical zone 103. In various implementations, thefirst and second optical zones 101 and 103 can be offset with respect toeach other along a z-axis (shown), such that the first and secondoptical zones 101 and 103 are physically discontinuous. Likewise, thesurface of the lens is not smooth at this location and instead has anabrupt discontinuity in the surface gradient. Without any loss ofgenerality, in various cases the power of the first optical zone 101 canbe smaller than the power of the second optical zone 103 such that thesecond optical zone 103 has more addition power than the first opticalzone 101.

As the patient's gaze moves from viewing objects at far distances toviewing objects at near distances, the patient's pupil traces a pathreferred to as the “natural convergence path” or “convergence path.”This path can refer to the vertical and horizontal gaze angle a patientuses to view objects that are straight ahead and at varying distances.Without any loss of generality, the projection of the convergence pathon the surface of the lens is oblique and extends along a line that iscoincident with the axis of symmetry of the first optical zone to a morenasal location disposed in the lower portion of the lens. Accordingly,the second optical zone 103 is disposed more nasally (or towards apatient's nose) in the lower portion of the lens.

Embodiments of flat-top bifocal lenses can have several disadvantages.For example, the optical power can abruptly change as the patient's gazemoves from viewing objects located at far distances through the firstoptical zone 101 to viewing objects located at near distances throughthe second optical zone 103. This abrupt change in optical power canresult in discontinuity of accommodation of the patient's eye, temporaryloss of image at intermediate distances between near and far distancesand/or a shift in the image or image jump. These effects can degrade theviewing experience. Moreover, only certain lens materials can be usedfor flat-top bifocal lenses. In addition, due to the discontinuity ofthe lens surface at the transition between the two zones, a high levelof effective residual cylinder power or aberrations can be encounteredas the eye transverses across this transition when following theconvergence path. Additionally, due to the discontinuous nature of theirsurface, flat-top bifocal lens cannot be manufactured using conventionalFreefrom techniques and machines available today in many processinglabs. It therefore follows that flat top bifocals cannot be manufacturedin a conventional processing lab using conventional sphericalsemi-finished blanks. Instead, semi-finished blanks alreadyincorporating the discontinuous properties of the lens surface have tobe manufactured for different materials. These semi-finished blanks maybe specific for manufacturing flat bifocal lenses, and as such can beless versatile than spherical semi-finished blanks that are widelyavailable in the market from which many continuous lens designs can bemanufactured using freeform technology. Accordingly, a patient may havelimited selection of materials and treatment options when orderingflat-top bifocal lenses. Furthermore, the optometrist or the lab thatmanufactures flat-top bifocal lenses may need to keep a full inventoryof specialized semi-finished optical lens blanks for each treatment(e.g. polarized, photochromic, and NXT lenses) option.

FIG. 2 shows a schematic representation of an embodiment of a blendedbifocal lens. In the illustrated embodiment of a blended bifocal lens,the first optical zone 101 and the second optical zone 103 are separatedby a blended zone 107. The blended zone 107 is border that surrounds thesecond optical zone 103. In the illustrated implementation, the secondoptical zone 103 has a central width of about 24 mm, and the blendedzone 107 has a uniform thickness of about 3 mm. The blended zone 107 canhave an optical power gradient such that there is a smooth transition ofoptical power from the first optical zone 101 to the second optical zone103. Accordingly, the presence of the blended zone 107 can alsoeliminate a physically discontinuity between first and second opticalzones 101 and 103 such that the separation between the first and secondoptical zones 101 and 103 is not visible. Additionally, the abruptdiscontinuity in optical power between the first optical zone 101 andthe second optical zone 103 can be avoided. While, the blended bifocallenses may be more aesthetically appealing over flat-top bifocal lenses,visual distortion, temporary loss of image and/or an image jump canoccur in the blended zone 107 as the patient's gaze shifts from thefirst optical zone 101 to the second optical zone 103. In addition, thepower gradients and/or the residual cylinder power in the blended zone107 can be high due to the narrow width of the blended zone 107. Thepatient's eye, as it traverses the convergence path in moving from thefirst optical zone 101 (distance vision zone) to the second optical zone103 (near vision zone) will traverse through the blended zone 107. Thehigh power gradients and/or the residual cylinder power in the blendedzone 107 can cause vision discomfort.

Progressive lenses available in the market today can overcome some ofthe disadvantages of bifocal lenses. FIG. 3(a) is a schematicillustration of an embodiment of a progressive lens further illustratingthe residual cylinder power or aberrations in the peripheral zones ofthe lens. A progressive lens includes a first optical zone 101 capableof providing far vision; a second optical zone 103 capable of providingnear vision; a corridor (or a transition zone) 111 connecting the firstand the second optical zones 101 and 103 and one or more peripheralzones 109 a and 109 b disposed about the corridor 111. The corridor 111is a region on the surface of the lens between the first optical zone101 and the second optical zone 103 where the optical addition powergradually increases (e.g., monotonically increases or linearlyincreases) as the patient's gaze moves from far vision to near visionalong the natural convergence path while the maximum residual cylinderpower and/or aberrations is below a threshold. The threshold can beabout 0.5 Diopter, about 0.25 Diopter or about 0.12 Diopter. The opticaladdition power gradient and size of the corridor 111 is configured suchthat objects at intermediate distance (for example between about 2 feetand about 6 feet) can be viewed comfortably through the corridor 111.The length and/or width of the corridor 111 for a progressive lens canbe adjusted such that peripheral zones 109 have residual cylinder powersand/or aberrations below a threshold.

In various implementations of available progressive lenses, theseparation between the first optical zone 101, the corridor 111 and thesecond optical zone 103 is not visible. Thus, such implementations ofprogressive lenses may be aesthetically pleasing. Furthermore, since theoptical power transitions smoothly and continuously across the firstoptical zone 101, the corridor 111 and the second optical zone 103 alongthe convergence path of the patient's eye, visual distortion and othereffects such as loss of image, image jump are eliminated orsignificantly reduced when a patient's gaze shifts from far vision tonear vision. However, in most progressive lenses, the second opticalzone 101 occupies a smaller portion of the surface area of theprogressive lens as compared to the portion of the surface area of theprogressive lens occupied by the first optical zone. In variousimplementations, the area of the second optical zone 103 can besignificantly smaller than the area of the first optical zone 101. Inaddition, due to the long corridor between the first optical zone 101and the second optical zone 103, a patient may have to lower his/hergaze considerably when transitioning from a distance vision state to anear vision state. This can cause discomfort to some patients.

The embodiment of the progressive lens illustrated in FIG. 3(a) includestwo peripheral zone 109 a and 109 b disposed on either side of thecorridor 111. The peripheral zone 109 a is disposed nasally while theperipheral zone 109 b is disposed temporally. FIG. 3(a) illustrates theresidual cylinder power in the peripheral zones 109 a and 109 b ascontours. The outermost contour indicates the boundary of the regionhaving least residual cylinder power while the inner most contourindicates the boundary of the region having maximum residual cylinderpower. In the embodiment illustrated in FIG. 3(a), region 110 a has themaximum residual cylinder power in the nasal peripheral zone and region110 b has the maximum residual cylinder power in the temporal peripheralzone.

FIG. 3(b) illustrates the schematic contour plot of the addition powerin the different portions of the embodiment of progressive lens shown inFIG. 3(a). Different contours indicate the boundaries of regions withdifferent optical addition powers. The region 110 c of the secondoptical zone corresponds to the region with maximum addition power. Theoptical addition power progressively decreases away from the region 110c towards the peripheral zones 109 a and 109 b. It is noted from FIG.3(b) that the addition power in the corridor 111 increases gradually(e.g., monotonically or linearly) from the first optical zone 101 to thesecond optical zone, as discussed above.

Various embodiments disclosed herein provide quasi progressive lensesthat overcome some of the disadvantages of bifocal lenses andprogressive lenses as discussed below. FIGS. 4(a) and 4(b) schematicallyillustrate different embodiments of a quasi progressive lens having afirst optical zone 101 capable of providing distance vision (oralternately intermediate distance vision in some embodiments) connectedto a second optical zone 103 capable of providing near vision (oralternately intermediate distance vision in some embodiments) by atransition zone 113. The first optical zone 101 can be referred to asthe far vision zone when configured to provide distance vision. Thesecond optical zone 103 can be referred to as the near vision zone whenconfigured to provide near vision. As used herein, the transition zone113 is a region on the surface of the quasi progressive lens between thefirst optical zone 101 and the second optical zone 103 where the opticaladdition power gradually increases (e.g., monotonically increases orlinearly increases) as the patient's gaze moves from far vision to nearvision along the natural convergence path while the maximum residualcylinder power and/or aberrations is below a threshold. The thresholdcan be about 0.5 Diopter, about 0.25 Diopter or about 0.12 Diopter.

The embodiment illustrated in FIG. 4(a) includes two distinct andseparated peripheral zones 109 a (disposed nasally) and 109 b (disposedtemporally). In the embodiment illustrated in FIG. 4(b) the secondoptical zone 103 is disposed with respect to the lower edge of the lenssuch that the two distinct peripheral zones 109 a (disposed nasally) and109 b (disposed temporally) are connected along the lower edge of thelens to form a single peripheral zone 109. In various implementations,the first optical zone 101, the second optical zone 103, the transitionzone 113 and the peripheral zones 109 a and 109 b are formed on the samesurface (either front surface or back surface) of a lens. The firstoptical zone 101, the second optical zone 103, the transition zone 113and the peripheral zones 109 a and 109 b are formed on the surface ofthe lens blank such that the surface of the lens blank appears smoothwithout any steps, indentations, or protrusions.

Embodiments of quasi progressive lenses have several advantages overbifocal lenses. For example, the transition zone 113 connecting thefirst and second optical zones 101 and 103 advantageously avoidsgeometric singularities such as a singular point or line between thefirst and second optical zones 101 and 103. The geometric differencesbetween quasi progressive lens, flat-top bifocal lens and a blendedbifocal lens are illustrated in FIGS. 5(a), 5(b) and 5(c) whichschematically illustrate cross-sectional views of an embodiment of aflat-top bifocal lens, an embodiment of a blended bifocal lens and anembodiment of a quasi progressive lens, respectively. As illustrated inFIG. 5(a), the first and second optical zones 101 and 103 for theillustrated embodiment of a flat-top bifocal lens are separated by avisible step and edge 105 which represents a line of physicaldiscontinuity in the surface and accompanying optical discontinuity.

As noted from FIG. 5(a), the surface of the lens including the slope ofthe surface of the lens (also referred to as prism) and the opticalpower, which is correlated to the second derivate of the surface of thelens, transition abruptly across the line 105. Additionally, the surfaceof the lens itself has a discontinuity due to the second optical zone103 being physically offset from the first optical zone 101 by adistance measured in the z direction (see z-axis).

In contrast, as noted from FIG. 5(b), a blended bifocal lens does notexhibit a physical step discontinuity between the first and secondoptical zones 101 and 103. Instead a smooth transition is providedbetween the first and second optical zones 101 and 103. However, theoptical power as well as the prism changes rapidly across the blendedzone 107. This rapid change in the surface introduces high levels ofresidual cylinder power or aberrations which can lead to disadvantageousoptical effects.

As noted from FIG. 5(c), the first and second optical zones 101 and 103are not physically offset with respect to each other thus there is nophysical discontinuity in the surface of the lens. In fact, thetransition zone 113 connects the first and the second optical zone 101and 103 continuously to form a smooth surface. Additionally, the slopeof the surface of the lens (prism) also varies continuously across thetransition zone 113. The transition zone 113 can also be devoid ofdiscontinuity in the surface curvature. Additionally, the transitionzone 113 can be devoid of discontinuity in the slope of the surfacecurvature. However, it is noted from FIG. 5(c) that the optical power,which is correlated with the second derivate of the surface of the lens,varies rapidly across the transition zone 113 between the first opticalzone 101 and the second optical zone 103.

Accordingly, the quasi progressive lens may be aesthetically morepleasing. Additionally, the continuity of the slope of the surface ofthe lens across the transition zone 113 may be advantageous in avoidingloss of image and/or image jumps as the patient's gaze shifts fromdistance vision to near vision through the convergence path. Inaddition, as a direct consequence of the overall continuity of the lens,less unwanted residual cylinder power or aberrations are encounteredalong the convergence path in the quasi progressive relative to the flattop and blended bifocal designs. Accordingly, a patient when using quasiprogressive lenses may be able to transition from distance vision tonear vision and experience less distortion and have a more positiveviewing experience as compared to when using conventional blendedbifocal as well as flat-top bifocal lenses.

The length of the transition zone 113 can be obtained by analyzingmeasurements of the addition power in the first and second optical zones101 and 103 and in the transition zone 113. For example, one techniqueof measuring the length of the transition zone 113 includes startingfrom the first optical zone 101 and obtaining a first point in, adjacentto, and/or proximal to the first optical zone 101 along the convergencepath below the fitting point (FP) where the addition power has a lowerthreshold value and obtaining a second point in, adjacent to and/orproximal the second optical zone 103 where the addition power has anupper threshold value. The length of the transition zone 113 is thedistance between the first and second points. FIG. 6(a) schematicallyillustrates this technique of measuring the length of the transitionzone 113. In FIG. 6(a), the first point is indicated by the referencenumeral 115 and second point by reference numeral 117. The length of thetransition zone 113 for the embodiment illustrated in FIG. 6(a) is thedistance between the first point 115 and the second point 117.

In various embodiments, the lower threshold value can correspond to theminimum addition power. In various embodiments, the lower thresholdvalue can be between about 0 Diopter and about 0.25 Diopter (e.g., 0,0.01 Diopter, 0.03 Diopter, 0.05 Diopter, 0.1 Diopter, or 0.125Diopter). In various embodiments, the upper threshold value cancorrespond to the maximum addition power. In various embodiments, theupper threshold value can correspond to the maximum addition power minusa subtraction value. The subtraction value can be between about 0Diopter and 0.25 Diopter (e.g., between about 0 Diopter and about 0.25Diopter (e.g., 0, 0.01 Diopter, 0.03 Diopter, 0.05 Diopter, 0.1 Diopter,or 0.125 Diopter).

The width of the transition zone 113 can be obtained by measuring theresidual cylinder power in the peripheral zones 109 a and 109 b. Thewidth of the transition zone 113 is measured for a particular residualcylinder power or aberration threshold. In one technique of measuringthe width of the transition zone 113, a left most point of the temporalperipheral zone 109 b and a right most point of the nasal peripheralzone 109 a where the maximum residual cylinder power is below athreshold cylinder power is determined. The width of the transition zone113 for that threshold residual cylinder power is the distance betweenthe left most and right most points. FIG. 6(b) schematically illustratesthis technique of measuring the width of the transition zone 113. InFIG. 6(b), the left most point of the temporal peripheral zone 109 b atwhich the maximum residual cylinder power is below 0.5 Diopter isindicated by the reference numeral 119 and right most point of the nasalperipheral zone 109 a at which the maximum residual cylinder power isbelow 0.5 Diopter is indicated by the reference numeral 121. The widthof the transition zone 113 for the embodiment illustrated in FIG. 6(b)is the distance between the point 119 and the point 121. In variousembodiments of the quasi progressive lenses described herein, the widthof the transition zone 113 can be between about 0.1 mm and about 5 mm,between about 0.2 mm and about 4 mm, between about 0.2 mm and about 6mm, between about 0.5 mm and about 5 mm, or between about 0.5 mm andabout 4 mm for different threshold values of residual cylinder power.For example, referring to FIG. 6(b), the width of the transition zone113 where the maximum residual cylinder power is below a thresholdresidual cylinder power of 0.75 Diopter is greater than the width of thetransition zone 113 where the maximum residual cylinder power is below athreshold residual cylinder power of 0.5 Diopter. As another example,the width of the transition zone 113 where the maximum residual cylinderpower is below a threshold residual cylinder power of 1.0 Diopter isless than the width of the transition zone 113 where the maximumresidual cylinder power is below a threshold residual cylinder power of1.25 Diopter.

The transition zone 113 for various embodiments of quasi progressivelens has a longer length as compared with the length of the blended zone107 of blended bifocal lenses. Thus, the optical power gradient in thetransition zone 113 of an embodiment of a quasi progressive lens islower than the optical power gradient in the blended zone 107 of blendedbifocal lens. Accordingly, a patient may have less discomfort whentransitioning from a distance vision state to a near vision state whenusing quasi progressive lenses as compared to when using blended bifocallenses.

Furthermore, as discussed above, the presence of the transition zone 113allows a smooth and continuous transition between the first optical zone101 and the second optical zone 103 as shown in FIG. 5(c). Moreover, asdiscussed above with reference to FIG. 5(c), the length and shape of thetransition zone 113 in various embodiments of quasi progressive lensesis configured to provide a continuous and monotonic increase in opticalpower from the first optical zone 101 to the second optical zone 103without any physical surface discontinues (e.g., in z direction) or fastprism change. Accordingly, the embodiments of quasi progressive lensescan have reduced visual distortion along the convergence path (forexample, one order of magnitude lower) as compared to blended andflat-top bifocal lenses. Furthermore, the power change across theblended zone 107 of a blended bifocal lens can be fast and volatile ascompared to the power change across the transition zone 113 of a quasiprogressive lens which can result in increased distortion in a blendedbifocal lens along the convergence path as compared to a quasiprogressive lens. As used herein, visual distortions refer to the amountof residual cylinder power or aberrations. Reduced distortions includeresidual cylinder power or aberrations below an aberration threshold,such as, for example, about 1.0 Diopter, 0.75 Diopter, 0.5 Diopter, 0.25Diopter, or 0.125 Diopter. For example, the residual cylinder power oraberrations along the convergence path between the first optical zone101 and the second optical zone 103 can be greater than 5 Diopters forblended bifocal lenses having an addition power of about 2 Diopters andin theory infinite for flat-top bifocal lenses. In contrast, theresidual cylinder power or aberrations along the convergence pathbetween the first optical zone 101 and the second optical zone 103 forvarious embodiments of quasi progressive lenses described herein can beless than about 5 Diopters. For example, in various implementations ofquasi progressive lenses described herein, the residual cylinder poweror aberrations along the convergence path from the first optical zone101 to the second optical zone 103 can be less than or equal to about 1Diopter, less than or equal to about 0.75 Diopter, less than or equal toabout 0.5 Diopter, less than or equal to about 0.25 Diopter, less thanor equal to about 0.125 Diopter, etc.

FIGS. 7(a)-(b) and 8(a)-(b) illustrate the differences between anembodiment of a blended bifocal lens and an embodiment of a quasiprogressive lens. FIG. 7(b) illustrates a map of the residual cylinderpower for an embodiment of a quasi progressive lens. Embodiments of theblended bifocal lens can have high values for maximum residual cylinderpower in the blended zone 107 along the convergence path. For example,in some embodiments, the maximum residual cylinder power can be about10.64 Diopter in the blended zone 107 along the convergence path betweenthe first and the second optical zones 101 and 103. In contrast, asdiscussed above, for embodiments of quasi progressive lenses, theresidual cylinder power in the transition zone 113 which is along theconvergence path is reduced. In fact, as noted from FIG. 7(b), themaximum value of the residual cylinder power occurs in the peripheralzone for the embodiment of the quasi progressive lens which lies outsidethe convergence path. Accordingly, the embodiment of the quasiprogressive lens has a reduced visual distortion as compared to theembodiment of the blended bifocal lens and the residual distortion isdistributed off to the periphery. The variation of residual cylinderpower along the convergence path for an embodiment of a blended bifocallens and an embodiment of a quasi progressive lens is illustrated inFIGS. 8(a) and 8(b).

FIGS. 8(a) and 8(b) illustrate the variation of the optical additionpower and the residual cylinder power as a function of view angle invarious optical zones for an embodiment of a blended bifocal lens and anembodiment of a quasi progressive lens respectively. Referring to FIGS.8(a) and 8(b), the curve 2 shows the variation of optical addition poweras a function of view angle in various optical zones, while the curve 4shows the variation of residual cylinder power as a function of viewangle in various optical zones. The view angle corresponds to thevertical angle of gaze along the convergence path relative to thefitting point. A view angle of zero corresponds to a patient gazingstraight ahead at the horizon through the fitting point. The view anglecan also be considered as the angle that the line of sight makes withthe fitting point when the patient is viewing objects at variousdistances. The view angle can be correlated to the vertical distancefrom the fitting point the convergence path on the surface of the lens.

It is noted from FIG. 8(a) that for the embodiment of the blendedbifocal lens, the residual cylinder power in the blended zone 107 isgreater than 1.0 Diopter. In contrast, it is noted from FIG. 8(b) thatfor the embodiment of the quasi progressive lens, the residual cylinderpower in the transition zone 113 is less than 0.5 Diopter. Accordingly,the quasi progressive lens can have greater visual acuity along theconvergence path than the blended bifocal lens.

Various embodiments of quasi progressive lenses described herein canalso provide several benefits over progressive lenses. For example, aquasi progressive lens can provide larger and cleaner first and secondoptical zones 101 and 103 as compared to a progressive lens. Forexample, in various embodiments of a quasi progressive lens providing anoptical addition power greater than or equal to 1.75 Diopter, the sizeof the first optical zone 101 (or far vision zone) as characterized bythe horizontal width through the fitting point where the maximumresidual cylinder power or aberrations is below a threshold (e.g., 0.5Diopter) can be between about 30 mm and about 70 mm. In variousembodiments, for certain addition powers, the size of the first opticalzone 101 can be approximately equal to full width of the lens. Incontrast, in various embodiments of a progressive lens providing thesame optical addition power greater than or equal to 1.75 Diopter, thesize of the first optical zone 101 as characterized by the horizontalwidth through the fitting point where the maximum residual cylinderpower or aberrations is below a threshold (e.g., 0.5 Diopter) is lessthan 20 mm. More particularly, as shown in Table 2 below, in variousimplementations of quasi progressive lenses, the width of the secondoptical zone 103 having certain addition power for providing near visionand maximum residual cylinder power or aberrations below a threshold(e.g., 0.5 Diopter) can be about 1.5 times to about 5 times larger thanthe second optical zone 103 (or near vision zone) having the sameaddition power and maximum residual cylinder power or aberrations belowa threshold (e.g., 0.5 Diopter) in various implementations ofprogressive lenses. The increase in the width of the second optical zone103 can advantageously provide a patient with a larger area throughwhich to view objects at near distance using various implementations ofquasi progressive lenses with a certain addition power as comparedvarious implementations of progressive lenses with the same additionpower.

The increase in the width of the second optical zone 103 having acertain addition power for various embodiments of quasi progressivelenses with respect to a width of the second optical zone 103 having acomparable addition power for various embodiments of progressive lensescan be attributed to the decreased width of the transition zone 113 ofthe quasi progressive lens as compared to the width of the corridor 111of a progressive lens. In comparison to the corridor 111 of anembodiment of a progressive lens, the transition zone of an embodimentof a quasi progressive lens can be significantly shorter and narrower.For example, the length of the transition zone 113 for variousembodiments of quasi progressive lenses can be between about 3 mm andabout 10 mm (e.g., between about 5 mm and about 8 mm, between about 6 mmand about 8 mm, between about 4 mm and about 8 mm, about 4 mm, about 5mm, about 6 mm, about 7 mm and about 8 mm).

The reduced length of the transition zone 113 also enables less movementof the gaze from the first optical zone 101 to reach the second opticalzone 103 in comparison to embodiments of progressive lenses. Thisreduction in travel can decrease the time required by a patient's eye totransition from a distant viewing state to a near viewing state andallow viewing near objects at more ergonomic angles of gaze.

One disadvantage for the quasi progressive lens, however, results fromthe short length of the transition zone 113. To produce the change inpower from the first zone 101 to the second optical zone 103 over theshort length entails a higher power gradient than for a conventionalprogressive lens. Table 1 below provides the minimum vertical powergradient along the convergence path for various values of opticaladdition power for an embodiment of a quasi progressive lens. As aconsequence, in contrast to embodiments of progressive lenses, objectsat intermediate distances cannot be viewed comfortably through thetransition zone 113 due to the reduced spatial dimensions of thetransition zone 113 and high optical power gradients in the transitionzone 113. As noted from Table 1 below, the minimum vertical powergradient along the convergence path increases as the optical additionpower increases. For example for an optical addition power of 0.75Diopter, the minimum vertical power gradient is about 0.08 Diopter/mm.As another example for an optical addition power of 4.0 Diopter, theminimum vertical power gradient is about 0.44 Diopter/mm. The opticaladdition power and the minimum vertical gradient can include valuesbetween the values set forth in Table 1 below. Accordingly, variousembodiments may include ranges established by any of these values.

TABLE 1 Minimum vertical power gradient along the convergence path inDiopter/mm for various values of optical addition power. OpticalAddition power Minimum vertical gradient along the [Diopter] convergencepath [Diopter/mm] 0.75 0.08 1 0.11 1.25 0.14 1.5 0.17 1.75 0.19 2 0.222.25 0.25 2.5 0.28 2.75 0.31 3 0.33 3.25 0.36 3.5 0.39 3.75 0.42 4 0.44

Table 2 below presents a comparison of various parameters of threedifferent embodiments of quasi progressive lenses with an embodiment ofa progressive lens. The embodiment of a progressive lens is an extremelyshort progressive lens with a corridor length of 11 mm (e.g., ShamirAutograph II™ 11). The first embodiment of the quasi progressive lenshas a near vision zone size of about 20 mm and a transition zone lengthof about 10 mm. The second embodiment of the quasi progressive lens hasnear vision zone size of about 20 mm and a transition zone with a lengthof about 7 mm. The third embodiment of the quasi progressive lens has anear vision zone size of about 15 mm and a transition zone with a lengthof about 5 mm. For the sake of comparison, the embodiments of theprogressive lens and the quasi progressive lenses have a far visionpower prescription of zero. Accordingly, the embodiments of theprogressive lens and the quasi progressive lenses can be considered asplanar lens at the first optical zone (or far vision zone). Theembodiments of the progressive lens and the quasi progressive lens, areconsidered to have a base power of about 4.0 Diopter and addition powersof about 1.0 Diopter, about 2.0 Diopter, and about 3.0 Diopter.

The corridor length of the progressive lens and the length of thetransition zone of the embodiments of the quasi progressive lens aremeasured along the convergence path starting from the lowest point belowthe fitting point where the addition power has a value of 0.1 Diopter toa point along the convergence path in the near vision zone having anaddition power equal to the maximum addition power minus 0.1 Diopter.The corridor width of the progressive lens and the width of thetransition zone of the embodiments of the quasi progressive lens aremeasured for two different aberration thresholds. In Table 2 below thevalues of the width for the corridor and the transition zone providedwithin parenthesis are measured within an aberration threshold of about0.5 Diopter. In Table 2 below the values of the width for the corridorand the transition zone that are provided without parenthesis aremeasured within an aberration threshold of about 1.0 Diopter. The farvision zone sized is characterized by the horizontal width of the farvision zone passing through the fitting point (FP) where the residualcylinder power is less than 0.5 Diopter. The near vision zone size ischaracterized by the horizontal width of a line passing through the nearreference point (NRP) where the addition power is not less than themaximum addition power (e.g., 1.0 Diopter, 2.0 Diopter or 3.0 Diopter)minus 0.25 Diopter. Alternatively, in various embodiments, the nearvision zone size can be characterized by the width through the centroidof an area of the second optical zone 103 (or near vision zone) wherethe addition power is not less than the maximum addition power (e.g.,1.0 Diopter, 2.0 Diopter or 3.0 Diopter) minus 0.25 Diopter. The maximumresidual cylinder corresponds to the maximum cylindrical aberrations inthe peripheral zones 109. The various parameters set forth below such ascorridor/transition zone width, far vision zone size, near vision zonesize, addition power and maximum residual cylinder power can includevalues between the values set forth in Table 2 below. Accordingly,various embodiments may include ranges established by any of thesevalues.

TABLE 2 Comparison of various parameters of three different embodimentsof quasi progressive lenses with an embodiment of a progressive lens.Progressive, Quasi Quasi Quasi extreme short Progressive, Progressive,Progressive, Autograph 20 mm 20 mm 15 mm Design: II ™ segment segmentsegment Corridor/Transition 11 10 7 5 zone Length [mm] Addition 1Corridor/ N.A. 6.7 4.4 5.4 [Diopter] Transition (40.6) (2.9) (2.2) (2.5)zone Width [mm] Far Vision 40.6 62.5 54.5 48.4 Zone Size [mm] NearVision 10 30 24 17 Zone Size [mm] Maximum 0.90 2.84 2.99 2.37 ResidualCylinder [D] Addition 2 Corridor/ 4.4 3.3 2.2 2.4 [Diopter] Transition(2.0) (2.0) (1.0) (1.0) zone Width [mm] Far Vision 7.8 44.5 44.6 39.9Zone Size [mm] Near Vision 8 28 22 15 zone Size [mm] Maximum 1.90 5.715.94 4.76 Residual Cylinder [D] Addition 3 Corridor/ 2.6 2.1 1.7 1.5[Diopter] Transition (1.1) (1.2) (0.7) (0.0) zone Width [mm] Far Vision5.0 55.6 38.4 33.8 Zone Size [mm] Near Vision 5 27 20 14 zone Size [mm]Maximum 2.87 8.56 8.09 7.15 Residual Cylinder [Diopter]

It is noted from Table 2, that for all values of addition powers (e.g.,1.0 Diopter, 2.0 Diopter or 3.0 Diopter) the width of the corridor forthe embodiment of the progressive lens is significantly wider than thewidth of the transition zone for any of the three embodiments of quasiprogressive lenses. It is further noted that the embodiment of theprogressive lens has a much smaller near vision zone size than the threeembodiments of quasi progressive lenses. Accordingly, the optical zonethat provides near vision for the three embodiments of the quasiprogressive lens is larger than the optical zone that provides nearvision for the embodiment of the progressive lens.

The residual cylinder power in the peripheral regions of the lens dependon the length of the transition zone. Shortening the length of thetransition zone can increase the residual cylinder power in theperiphery. This effect is observed from Table 2, where the maximumresidual cylinder has a reduced value for the embodiment of theprogressive lens at all values of addition power as compared to thethree embodiments of the quasi progressive lens. The width of thetransition zone for a given length of the transition zone can alsoaffect the maximum residual cylinder. For example, a wider transitionzone can increase the maximum residual cylinder.

As discussed above, a short transition zone can lead to high powergradients in the transition zone which can cause visual distortions whenthe gaze shifts between distance vision and the near vision. Thus, byvirtue of its length, the transition zone is optically non-functionalfor most patients in that it does not allow comfortably viewing objectsthrough the transition zone. In various embodiments of quasi progressivelenses, objects at intermediate distances viewed through the transitionzone may appear distorted, blurred, unclear, and/or unresolved. Asdiscussed above with reference to FIGS. 6(a) and 6(b), the width of thetransition zone is given by the distance between two points of theperipheral region that have residual cylinder power or aberrations lessthan an aberration threshold. In various embodiments, the aberrationthreshold can be less than or equal to about 0.125 Diopter, less than orequal to about 0.25 Diopter, less than or equal to about 0.5 Diopter,less than or equal to about 0.75 Diopter or less than or equal to about1 Diopter. Reducing the width of the transition zone reduce the residualcylinder power or aberrations in the peripheral regions.

The first optical zone 101, the second optical zone 103, the transitionzone 113 and the peripheral zones 109 a and 109 b can be processed onthe surface of the lens using freeform technology. In implementingfreeform technology, in various embodiments, a surface grid resolutionis determined for designing and manufacturing the lens. The size of thesurface grid elements can affect the accuracy of the features formed onthe surface. For example, a finer grid obtained by decreasing the sizeof the grid elements can increase the accuracy of the features formed onthe surface. In contrast, a coarser surface grid obtained by increasingthe size of the grid elements may reduce the accuracy of the featuresformed on the surface. However, a coarser grid may shorten design and/orproduction time and may be more cost effective from a manufacturingstandpoint. For example, a grid resolution of 1 mm can be sufficient forthe spatial frequency required for the optical features of quasiprogressive lenses. Since, the size of the features of quasi progressivelenses are generally of the same order as the size of the features ofprogressive lenses, the embodiments of quasi progressive lensesdescribed herein can be manufactured on the freeform machinery in themanufacturing labs using the same manufacturing profiles and parametersused for producing progressive lenses. Manufacturing quasi progressivelenses using freeform technology can also provide significant reductionin manufacturing time and costs as compared to manufacturing blendedbifocal lenses since blended bifocal designs have smaller/sharperoptical features in the blending zone as compared to the opticalfeatures of quasi progressive lenses.

Example Embodiments of a Quasi Progressive Lens

As discussed above, various embodiments of a quasi progressive lens caninclude a first optical zone disposed in the upper portion of a surface(e.g., forward or rearward) of the lens, a second optical zone disposedin the lower portion of the same surface and a short and narrowtransition zone connecting the first and second optical zone. The bodyof the lens can comprise a variety of optical materials including butnot limited to CR-39, Trivex, 1.56, SuperLite 1.60, SuperLite 1.67,Polycarbonate, and SuperLite 1.74. Other optical materials can also beused. The body of the lens can be subject to a variety of pre-treatmentsincluding but not limited to Clear™, Transitions™ VI and VII (Gray,Brown), Transitions XtrActive™, Transitions Vantage™, Polarized (Gray,Brown) and Drivewear™ The lens body can comprise tints or coating (e.g.,hard anti-scratch coating, anti-reflection coating, etc.).

The first optical zone is configured to provide far or distance vision,such as, for example, at distances beyond about 20 feet. In variousembodiments, the first optical zone can be configured to provideintermediate distance vision, such as, for example, at distances betweenabout 2 feet and about 20 feet. The first optical zone can have aspherical power range between about −20 Diopter and about 20 Diopter tocorrect for refractive errors in a patient's eye. In addition, the firstoptical zone can have a cylinder power in the range between about −10Diopter to about 0 Diopter or 0 Diopter to about +10 Diopter to correctfor astigmatic errors in the patient's eye. The first optical zone canalso include an area having a residual cylinder power or aberrationsless than or equal to about 0.25 Diopter, less than or equal to about0.12 Diopter, less than or equal to about 0.06 Diopter and/or less thanor equal to about 0.03 Diopter. The width of the first optical zone canvary between about 20 mm to about 70 mm depending on the surface area ofthe lens body, the width and height of the frame selected by the patientand the patient's facial structure and other physical characteristics.In various embodiments, the width of the first optical zone can begreater than or equal to 50 mm, greater than or equal to 40 mm orgreater than or equal to 30 mm. In various embodiments, the width of thefirst optical zone can include the full width of the lens. The height ofthe first optical zone can vary from about 6 degrees below the fittingpoint to about 30 degrees above the fitting point. For example, invarious embodiments, the height of the first optical zone can be betweenabout 3 degrees above the fitting point and about 20 degrees above thefitting point. As another example, in various embodiments, the height ofthe first optical zone can be between about 2 degrees below the fittingpoint and about 25 degrees above the fitting point. In variousembodiments, the bottom (or lower portion) of the first optical zone canextend below the fitting point. For example, the bottom (or lowerportion) of the first optical zone can extend up to about 6 mm below thefitting point. In various embodiments, the bottom (or lower portion) ofthe first optical zone can extend between about 2 mm to about 3 mm belowthe fitting point.

The second optical zone is configured to provide near vision, such as,for example, at distances of about 16 inches. In various embodiments,the second optical zone can be configured to provide intermediatedistance vision, such as, for example, at distances between about 2 feetand about 20 feet. In various embodiments, the second optical zone canbe disposed nasally on the surface of the lens. The second optical zonecan have a variety of shapes such as, for example, circular, elliptical,D shape (with or without rounded edges), etc. The second optical zonecan have an additional spherical power in the range between greater than0 or 0.25 Diopter to about 4 Diopter relative to the spherical powerprovided by the first optical zone. The second optical zone can alsoinclude an area having a residual cylinder power or aberrations lessthan or equal to about 0.25 Diopter, less than or equal to about 0.12Diopter, less than or equal to about 0.06 Diopter and/or less than orequal to about 0.03 Diopter. The width of the second optical zone canvary between about 6 mm to about 40 mm. In various embodiments, thewidth of the second optical zone can be greater than, equal to or lessthan 12 mm, greater than, equal to or less than 15 mm, greater than,equal to or less than 20 mm or greater than, equal to or less than 24mm. In various embodiments, a nominal addition power of about 0.01Diopter, 0.03 Diopter, 0.06 Diopter, 0.1 Diopter or 0.25 Diopter isreached at a distance between about 4 mm and about 20 mm below thefitting point. For example, a nominal addition power can be reach at adistance of about 10 mm below the fitting point in some embodiments. Invarious embodiments of quasi progressive lenses a portion of the regionhaving the maximum addition power can be along the convergence path.

The transition zone connecting the first and second optical zones canhave a length between about 3 mm to about 10 mm. For example, a lengthof the transition zone can be between about 5 mm and about 8 mm. Thewidth of the transition zone with a threshold residual cylinder powerless than 1.0 Diopter can be less than or equal to about 4 mm. The widthof the transition zone with a threshold residual cylinder power lessthan 0.75 Diopter can be less than or equal to about 3 mm. The width ofthe transition zone with a threshold residual cylinder power less than0.5 Diopter can be less than or equal to about 2 mm. The width of thetransition zone with a threshold residual cylinder power less than 0.25Diopter can be less than or equal to about 1 mm. The transition zone caninclude an area having a residual cylinder power or aberrations lessthan or equal to about 1.0 Diopter, less than or equal to about 0.75Diopter, less than or equal to about 0.5 Diopter, less than or equal toabout 0.25 Diopter and/or less than or equal to about 0.12 Diopter.

Although a variety of examples are provided herein a wide range ofvariations are possible. For example, the width of near vision zoneproviding different addition powers greater than 0.5 Diopter (e.g., anyone of the ranges between 0.75 Diopter to about 1.5 Diopter, between1.75 Diopter to about 2.5 Diopter or between 2.75 Diopter to about 4.0Diopter) can be about 10 mm, 12 mm, 15 mm, 20 mm, 25 mm, 30 mm, 35 mm,40 mm, etc. as well as values in between any combination of thesewidths. As another example, the width of the far vision zone providingdifferent addition powers greater than 0.5 Diopter (e.g., any one of theranges between 0.75 Diopter to about 1.5 Diopter, between 1.75 Diopterto about 2.5 Diopter or between 2.75 Diopter to about 4.0 Diopter) canbe 20 mm, 25 mm, 30 mm, 35 mm, 40 mm, 45 mm, 50 mm, 55 mm, 60 mm, 65 mm,70 mm etc. as well as values in between any combination of these widths.

As yet another example, the length of the transition zone for a lensproviding an addition power greater than about 0.5 Diopter (e.g., anyone of the ranges between 0.75 Diopter to about 1.5 Diopter, between1.75 Diopter to about 2.5 Diopter or between 2.75 Diopter to about 4.0Diopter) can be about 3 mm, 4 mm, 5 mm, 6 mm, 7 mm, 8 mm, etc. as wellas values in between any combination of these lengths.

As another example, the width of the transition zone with a thresholdresidual cylinder power less than any of 0.5 Diopter, 1.0 Diopter or1.25 Diopter for a lens providing an addition power of 0.5 Diopter(e.g., any one of the ranges between 0.75 Diopter to about 1.5 Diopter,between 1.75 Diopter to about 2.5 Diopter or between 2.75 Diopter toabout 4.0 Diopter) can be about 0.5 mm, 1 mm, 2 mm, 3 mm, 4 mm as wellas values in between any combination of these widths.

As another example, the maximum residual cylinder power in theperipheral zone can be about 1.5 Diopter, 2.0 Diopter, 2.5 Diopter, 3.0Diopter, 4.0 Diopter, 5.0 Diopter, 6.0 Diopter, 7.0 Diopter, 8.0Diopter, 9.0 Diopter, 10.0 Diopter, 11.0 Diopter, 12.0 Diopter, etc. aswell as values in between any combination of maximum residual cylinderpowers. In various embodiments, the residual cylinder power in theperipheral zone can be greater than 1.5 Diopter, 2.0 Diopter, 2.5Diopter, 3.0 Diopter, 4.0 Diopter, 5.0 Diopter, 6.0 Diopter, 7.0Diopter, 8.0 Diopter, 9.0 Diopter, 10.0 Diopter or 11.0 Diopter.

The above presents a description of systems and methods contemplated forcarrying out the concepts disclosed herein, and of the manner andprocess of making and using it, in such full, clear, concise, and exactterms as to enable any person skilled in the art to which it pertains tomake and use this invention. The systems and methods disclosed herein,however, are susceptible to modifications and alternate constructionsfrom that discussed above which are within the scope of the presentdisclosure. Consequently, it is not the intention to limit thisdisclosure to the particular embodiments disclosed. On the contrary, theintention is to cover modifications and alternate constructions comingwithin the spirit and scope of the disclosure as generally expressed bythe following claims, which particularly point out and distinctly claimthe subject matter of embodiments disclosed herein.

Although embodiments have been described and pictured in an exemplaryform with a certain degree of particularity, it should be understoodthat the present disclosure has been made by way of example, and thatnumerous changes in the details of construction and combination andarrangement of parts and steps may be made without departing from thespirit and scope of the disclosure as set forth in the claimshereinafter.

1.-65. (canceled)
 66. An ophthalmic lens comprising: a far optical zonecapable of providing far vision; a near optical zone capable ofproviding near vision; and a corridor connecting the far optical zoneand the near optical zone, the corridor having a length between 4 and 8mm, wherein the near optical zone has a width between 12 mm and 24 mmand has residual cylinder power less than 0.25 Diopter.
 67. Theophthalmic lens of claim 66, wherein the corridor has a power gradientextending from the far optical zone to the near optical zone with lowerpower closer to the far optical zone and higher power closer to the nearoptical zone.
 68. The ophthalmic lens of claim 66, wherein the faroptical zone has a width between 20 mm and 70 mm.
 69. The ophthalmiclens of claim 66, wherein the near optical zone provides an additionbetween 1.00 and 4.0 D.
 70. The ophthalmic lens of claim 66, wherein thenear optical zone has a width between 15 mm and 24 mm.
 71. Theophthalmic lens of claim 66, comprising a freeform lens having a backsurface comprising a freeform surface.
 72. The ophthalmic lens of claim66, wherein the near optical zone includes prism power for providingprism correction.
 73. The ophthalmic lens of claim 66, wherein thecorridor allows a smooth transition from the far optical zone to thenear optical zone.
 74. The ophthalmic lens of claim 66, wherein thecorridor does not allow comfortable gazing in mid-range distance betweenthe far and the near zones.
 75. The ophthalmic lens of claim 66, whereinthe corridor has a length between 4 and 6 mm.
 76. The ophthalmic lens ofclaim 66, wherein the corridor has a length of 4 mm.
 77. The ophthalmiclens of claim 66, wherein a length of the corridor is configured toprovide a residual cylinder less than 1 D.
 78. The ophthalmic lens ofclaim 66, wherein the corridor has a width between 1 mm to 4 mm withresidual cylinder of less than a threshold of 0.5 D.
 79. The ophthalmiclens of claim 66, wherein the corridor has a width between 3 mm to 8 mmwith residual cylinder of less than a threshold of 1 D.
 80. Theophthalmic lens of claim 66, wherein the corridor has a width between 1mm to 8 mm, wherein the near optical zone has a width between 12 mm to40 mm, and wherein the maximum residual cylinder of the lens is lessthan 8.56 D.